There are a number of instruments wherein distal jaws are remotely actuated to open and close them. A novel actuating system for a surgical instrument is described in U.S. Pat. No. 4,712,545 to Honkanen, which is commonly owned with the present invention and is incorporated herein by reference. Rather than rely on tiny pivot pins to hinge two jaws together, arcuate flanges and grooves pivotably interconnect the jaw members with a coupling member that also serves as an actuating member to drive the jaws together or apart, depending on the direction in which the coupling member is moved. Significant mechanical advantage is achieved by spreading the centers of rotation much farther apart than that which would be achieved using pivot pins mounted within the jaws.
Because the coupling member described in the Honkanen '545 Patent is a solid, rigid element which extends from the movable jaw member to a handle mechanism, the coupling member itself rises and falls over its entire length during operation of the jaws. The coupling member rises and falls within an open groove in the instrument. This is acceptable for many surgical procedures including arthroscopic knee surgery, but does not provide a fluid-tight seal between the distal and proximal ends of the instrument.
A gas-tight seal is desirable in some procedures such as laparoscopy and other surgical operations in which a pressure differential exists between the interior and the exterior of a patient. The pressure differential therefore is experienced between the distal and proximal ends of a laparoscopic instrument.
Grasper and Dissector surgical instrument for laparoscopy are available from Stryker Endoscopy, San Jose, Calif. The Stryker instruments have dual moving jaws which are connected together by a central pivot pin. Each movable jaw is separately interconnected by a pivot pin to the distal end of a link member. The two link members are interconnected at the proximal end with an actuator by a "T" projection of the actuator which fits into a recess within each link. The rise and fall motion of each link is relatively limited.